The present invention relates to an impregnated carbon brush with improved running properties and increased wear resistance for current pickup (collecting) devices on electrical machinery. Carbon brushes from hard-burnt carbon or electrographite are frequently impregnated with various organic or inorganic substances or mixtures, with the purpose of impregnation varying. Ordinarily, however, an improvement of running properties and increase in life of the brushes is to be achieved.
The purpose of impregnating the brushes with greases, oil or waxes is to produce a lubricant film on the collector running surface or on the slip ring. This improves the running behavior and reduces the wear. However, in many cases this improvement is not sufficient since, even when using high-melting greases or waxes the beneficial effect is present only for a limited period, e.g., when increased operating temperatures are present. In such cases, these means act mainly as start-up aids since they become liquid after a relatively short time due to the effect of temperature and leave the brushes. Another disadvantage with intermittent operation is a freezing of the brushes on the holder walls due to the impregnating medium having left.
It is, therefore, an object of the present invention to create a carbon brush which avoids these disadvantages and which contains an impregnating medium that does not depart during the entire running time of the brush even at increased operating temperatures.
Another object of the present invention is to provide a carbon brush of the foregoing character which may be economically fabricated and has a substantially long operating life.